What are the rules on hyphens in ages: 20-year-old...two hyphens?

4 answers

2

If the adjective phrase (twenty-year-old) comes before the noun it modifies, use hyphens AND no -s on 'old'; if the adjective phrase comes after the verb (usually be or some other non-action verb) AND not before a noun, don't use any hyphens and add -s on 'old.